He was sick but I didn't know then.

他病了，但我当时不知道。

youdao

I didn't know then.

当时我并不知道。

《新英汉大辞典》

Uncle Tony: Yeah, but I didn't know then!

是啊，我当时不知道啊！

youdao

Then you say, well why didn't they divide by 365, because I know there are 365 days in a year?

也许你们会问,为什么他们不除以365,因为一年有365天

耶鲁公开课 - 金融市场课程节选

and then I'd have a few weeks where, you know, I didn't have anything going on,

然后有几个星期，我几乎什么事都没有。

临时抱佛脚？也做过 - SpeakingMax英语口语达人

Of course, I didn't know that until I got to my car, and then my phone starts ringing.

CNN: 2 would-be passengers feel relief, sadness: 'It could have been me'

If she, a strong, career-oriented feminist who, with my dad, sacrificed a great deal for me to go to college was telling me to pay more attention to my romantic life, then what did she know that I didn't?

WSJ: Emily Esfahani Smith: Find a Man Today, Graduate Tomorrow

Ms. TORONTO: To call someone a macaca and then say that they didn't even know what it meant - I mean, you must think that we're all stupid.

NPR: Allen's Miscues Make for Close Race in Virginia